With the advent of the microprocessor, virtually all modern vehicles have come to utilize onboard computers to control and monitor engine and electrical system functions. Such vehicle onboard computers typically interface with a multiplicity of sensors and transducers, which continuously detect vehicle and engine operational parameters and provide representative electrical signals to the onboard computer. The data collected and processed by the onboard computer can be useful in the diagnosis of vehicle engine and electrical system malfunctions. Thus, the vehicle onboard computer typically includes a communication port connector that allows certain of the collected data to be transmitted to an independent computer analyzer, which may process the vehicle diagnostic data, store the vehicle diagnostic data, or present the vehicle diagnostic data in a visual format that can be interpreted by vehicle maintenance and repair technicians.
In conjunction with these technological developments, a variety of specialized computer analyzers, or vehicle diagnostic tools, have been developed and marketed to provide vehicle maintenance and repair technicians access to the vehicle diagnostic data available from the vehicle onboard computers. The current technology includes a variety of hand-held vehicle diagnostic tools with considerable processing capabilities, typically incorporating an integral display and capable of displaying the vehicle diagnostic data in a variety of graphical formats that allow vehicle technicians to view and interpret the data. Use of such vehicle diagnostic tools, frequently referred to as scan tools, has become the standard in vehicle diagnostics.
Because modern vehicles incorporate multiple electronic control modules to control the various vehicle systems, an onboard computer network is required to allow communication between the various electronic control modules. In order to facilitate the use of off-board test equipment, wiring harness connectors have been provided on vehicles to allow an off-board tester to be connected to an in-vehicle network. When computer control was introduced into the automotive industry, each manufacturer developed its own proprietary architecture and protocol for an in-vehicle network, and manufacturers had complete discretion to implement any communication connector with any combination of pin assignments. This proved inefficient and costly, so the various manufacturers collaborated to establish a set of standards for vehicle-based computer networks.
Subsequently, state, federal and foreign governments implemented legislation requiring network interface standards for On-Board Diagnostics (OBD). Generally, these statutes have required the adoption of a standard vehicle interface connector, or diagnostic link connector (DLC), for cars and light trucks sold in this country and much of the world, the Society of Automotive Engineers (SAE) J1962 connector. Since 1996, United States federal law and state laws require that the vehicle manufacturers equip vehicles with a sixteen-pin SAE J1962 connector, and that the in-vehicle network support at least one of several common network standards. As a result, most cars produced today include the J1962 connector as the diagnostic link between on-vehicle computers and off-vehicle test equipment, utilizing one or more network interface protocol standards.
Although the laws have standardized the connector, the current laws do not specify all of the pin assignments. As a result, even though virtually all cars and light trucks manufactured today have the same vehicle diagnostics connector, the various manufacturers continue to use different connector pin combinations to support communications with their in-vehicle networks. Thus, even though a vehicle diagnostic tester with a J1962 connector may be connected to virtually all vehicles manufactured since 1996, the data received on the individual connector pins differs from one vehicle manufacturer to another.
In order to address this issue, special vehicle diagnostics interface adapter harnesses have been developed that allow switching between the various connector pins on the vehicle interface and the off-board tester interface. However, in order to accommodate both pre-1996 vehicles and post-1996 vehicles, more than twenty different adapter harnesses may be required. In addition, in order to accommodate the various interface adapter harnesses, off-board test equipment inserts, such as the Smart System Inserts (SSI) made by the SPX Corporation of North Carolina, U.S.A. for use with its scan tools, or multiple discrete switches in the wiring harness are required to interface with the various in-vehicle networks. Accordingly, it is desirable to provide a vehicle diagnostics interface adapter that is capable of switching vehicle interface connector pins to the various diagnostic scan tool connector pins, requires fewer adapter harnesses and off-board test equipment inserts, has flexibility to accommodate future configuration changes, conserves space and is relatively inexpensive to manufacture.